1. Field of the Invention
This invention relates to a rotor of an electrical machine having a direct gas cooled rotor winding and more particularly this invention relates to a rotor of an electrical machine as described in the article "Luftgekuehlte Turbogeneratoren", published in "ETG-Fachberichte 3-Kraftwerks-Generatoren" VDE-Verlag GmbH-Berlin 1977, pp. 45-54, in particular FIGS. 8 and 10 on p. 52.
2. Discussion of Background
The known directly gas cooled rotor winding consists of individual conductors arranged one above the other, with one or two longitudinal ducts per conductor. The cooling gas enters on both sides underneath the end of the rotor winding and splits into two paths at the beginning of the rotor packet. Part of the gas flows through the winding end conductor and leaves the winding end space through special openings which are located in the pole zone in the rotor packet; the main part of the cooling gas quantity, however, enters the hollow conductors at the beginning of the rotor packet in order to flow out radially in the center of the rotor packet. The gas outlet part is shown in FIG. 10 of the publication mentioned above. It may be seen from this representation that all the conductors of one layer in the center of the rotor have solid intermediate conductor pieces and the two cooling ducts of each conductor position are penetrated at the sides at the connection point with the intermediate conductor pieces. The cooling ducts enter radially outwards extending ducts which are located symmetrically with respect to the longitudinal direction of the conductors. These radial ducts are formed by millings in the solid intermediate conductor pieces lying above each of them nd by the groove closure wedges. Because of the gas supply on both sides, connecting sections of varying length are not so intensively cooled, depending on the position of the conductor in the groove. This causes an additional increase in temperature (hot spot) which finally determines the thermal load limit which can be accepted by the rotor winding.